There are implantable medical devices that are loaded with or are otherwise able to administer or deliver a large or unlimited amount of therapy. For example, an implanted drug pump could contain many years worth of drug, or an inductively powered, rechargeable, or primary cell implantable stimulator could deliver therapy in perpetuity as governed by the external controller, charger or battery life. These types of implanted devices present benefits to the patient and the healthcare system in that the often invasive implantation procedures are limited. However, they pose some unique clinical risks in that the patient carries with them, either within the implant or by virtue of the implant, a much larger quantity or amount of therapy than would otherwise be prescribed by a physician, an insurer or a manufacturer.
An implantable neurostimulator used to treat headaches can be used very frequently for the rest of the patient's lifetime. Given the unlimited nature of therapy delivered in this manner, the patient could choose to activate the neurostimulator when it is not needed. Without some limitation mechanism, the medical device may become much like an over-the-counter pharmaceutical where usage is entirely up to the user.
The inability to limit use of such medical devices poses potential clinical risks to the patient, such as over-use (if over use is a clinical problem) that leads to ineffective therapy over time at therapy levels that were once effective. The absence of usage limits may also fatigue the internal components of the device, resulting in a shorter therapeutic lifetime. Further, it can pose increased financial burden to the healthcare system due to poorer clinical outcomes or more frequent device failures. Finally, it can also present financial constraints on patients, for example if the device is priced based on all potential uses of the device, or constraints on an insurer or the manufacturer if patients use the device much more than intended.